Exhaust gas emitted from an internal combustion engine is a heterogeneous mixture that contains gaseous emissions such as carbon monoxide (“CO”), unburned hydrocarbons (“HC”) and oxides of nitrogen (“NOx”) as well as condensed phase materials (liquids and solids) that constitute particulate matter. Catalyst compositions typically disposed on catalyst supports or substrates are provided in a diesel engine exhaust system to convert certain, or all of these exhaust constituents into non-regulated exhaust gas components.
Particulate filters remove the particulate matter from the exhaust gas. The particulate matter accumulates within the particulate filter. The accumulated particulate matter causes an increase in exhaust system backpressure experienced by the engine. To address this increase, the particulate filter is periodically cleaned, or regenerated. Regeneration of a particulate filter in vehicle applications is typically automatic and is controlled by an engine or other controller based on signals generated by engine and/or exhaust system sensors. The regeneration event involves increasing the temperature of the particulate filter to levels that are often above 600° C. in order to burn the accumulated particulates.
In some cases, an increase in exhaust flow during regeneration may decrease the temperature within the particulate filter thus, causing the regeneration to be extinguished. Accordingly, it is desirable to provide methods and systems for re-striking the regeneration after the regeneration has been extinguished to complete the regeneration.